1. Field of Invention
The present invention relates to a variable valve lift device and a valve apparatus for a vehicle engine using the same, and more particularly, to a variable valve lift device and a valve apparatus for a vehicle engine using the same, which allow high lift modes and low lift modes of intake and exhaust valves to be implemented by two rocker arms operated by hydraulic pressure.
2. Description of Related Art
In general, in an engine of a vehicle, a combustion chamber configured to generate power by combusting fuel is provided, and a valve train is provided which includes an intake valve, which controls an inflow of air, or a mixture of air and fuel which flows into the combustion chamber, and an exhaust valve which controls an outflow of exhaust gas discharged from the combustion chamber.
In addition, the combustion chamber is opened and closed while the intake and exhaust valves of the valve train are operated by a cam which is moved together with rotational motion of a crankshaft rotated by receiving power generated by the combustion of fuel.
As the cam is formed to have a predetermined profile, the intake and exhaust valves always have a predetermined lift value, and an amount of inflow and outflow of air and exhaust gas, which flows into and out of the combustion chamber through the intake and exhaust valves, are set to be a predetermined amount in accordance with the lift value of the cam.
When the lift values of the intake and exhaust valves are appropriately adjusted in accordance with an operational state of an engine for a vehicle, fuel efficiency and output of the engine may be increased, and therefore a variable valve lift device configured to adjust the lift value of intake and exhaust valves in accordance with an operational state of the engine is being proposed.
The variable valve lift device may be classified into a hydraulic device or a mechanical device based on an operational power source, and in a case of the hydraulic variable valve lift device, a structurally improved method is necessary which may increase valve lift loads, and improve operational reliability.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.